1. Field of the Invention
The present invention relates to a process for fabrication of a connector terminal which is to be connected to a substrate by soldering, and to the connector terminal.
2. Description of the Related Art
On a substrate of, for example, an electronic device or electronic circuit, for example, a surface-mounted connector (“SMT connector”) is mounted by soldering.
Such a connector is provided with a connector housing, which is formed in, for example, a substantially rectangular box shape, and a plurality of connector terminals (terminals), which are inserted into assembly holes formed at a side of the connector housing to be mounted. For this structure, the plurality of connector terminals are respectively subjected to a plating treatment, are respectively inflected downward (toward the substrate), and distal end portions thereof are fixed to an upper face of the substrate by soldering (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2001-110491).
Now, a plurality of connection terminals as described above is fabricated by being punched from a plate material. When this plurality of connector terminals is to be fabricated, first, a plate material (a strip member) which has not been plating-processed is punched by a pressing process to form workpieces which are linked in a comb shape (a concatenated form). After this pressing process (i.e., after punching of the plate material), whole peripheral surfaces of the workpieces (both plate material surface portions and punch-cut surface portions) still have not been plating-processed. Thereafter, the whole peripheral surfaces (both the plate material surface portions and the punch-cut surface portions) are subjected to plating by a “post-plating treatment”. After that, if the plating is tin-plating, a special treatment is applied in order to suppress the formation of whiskers. The workpieces which have been processed as described hereabove are subjected to bending processing in accordance with the connector that is to be surface-mounted, and are employed as connector terminals.
Thus, according to a conventional fabrication process, plating can be reliably applied over whole peripheral surfaces of connector terminals.
However, in a conventional fabrication process as described above, a plating layer is formed at the whole peripheral surfaces of the workpieces by the “post-plating treatment”, the workpieces being in the complex shape linked in a comb form and being after the pressing process (i.e., after punching of the plate material). Consequently, a film thickness of the plating layer varies between regions of post-plating, and it is difficult to make the film thickness of the plating layer uniform overall. When the film thickness of the plating layer is uneven, then, for example, insertion/extraction forces between the connector terminals and female terminals which correspond with the connector terminals are increased, which is not preferable in regard to an operation of fitting these connectors with the female connectors corresponding to the connectors.
Further, this post-plating treatment is problematic in that processing costs are much higher than with a pre-plating treatment. Accordingly, fabrication of connector terminals by punching workpieces from a plate material which has been subjected to a pre-plating treatment has been considered. However, cut surface portions thereof are, naturally, in an unplated state and, if a plating layer at those portions is necessary (for example, when such cut surface portions are regions which are to be soldered), the post-plating treatment cannot be omitted. Therefore, the problem of treatment costs being incurred due to performance of the post-plating treatment is fundamentally insoluble, and measures for suppressing costs of plating processing, and hence fabrication costs of connector terminals, have been sought.
Further still, when the workpieces are subjected to a tin-plating treatment as the post-plating treatment, it is necessary to apply the special treatment for suppressing the formation of whiskers to the plating layer. Consequently, there is a problem in that processing costs are further raised.